Best bang for the buck, 113, 117,120, 124

[BVHOG]

There is a lot to be considered here, first off you came to a performance forum and you will be guided accordingly. Yes big cubes are great but they are not for everyone.
First off, you mentioned it is a touring bike, I would assume touring in all conditions. Will you build this motor to run on any gas and run cool enough to retain longevity? This could mean a lower comp build, a real oil cooler setup or even fans. Will you need to install an aftermarket clutch? likely and do you mind the extra lever pull that is most times necessary?  Will the rest of your drive train hold up to long term touring? I have two bikes in right now with failed output bearings on the cruise drive trans.
Will you need a chain setup if you are an aggressive rider?  A good 113 build will make most people very happy for both cruising and longevity, unhappy when your buddy with the 124 passes you.
A 124 will make you very happy when you roll that throttle, not so happy sitting in line at Sturgis looking for a parking spot
As far as best bang for the buck the price of these engine sizes will vary little.
Whatever you decide, build this motor to run cool and don't push it to the bleeding edge for what after all is a street bike.

[Buffalo]

My S&S T124 HC crate motor, carbed, has never run over 195 degrees while moving. It typically runs right at 190, even on 100 degree days. The hottest I've ever seen it (Autometer gauge) is 235, sitting in traffic in Sturgis for 35 minutes. It was 105 degrees that day, and as soon as I had the bike rolling, it dropped back to 195 within a mile.
I've run it without issue on 87 octane fuel several times when forced to (nothing else available), it ran fine. I wouldn't hammer on it with 87, but it cruised at 80 mph no problems.
I've run it on Sinclair 91 (worst US gas I ever used) and the equivilant UAP "Potty mouth" 93 they sell here in Canada.
In both cases, the motor even sounded different, mileage went to hell, and I've never used it again. It stil did not run hot.  fwiw  Buffalo

[planemech]

There is a lot to be considered here, first off you came to a performance forum and you will be guided accordingly. Yes big cubes are great but they are not for everyone.
First off, you mentioned it is a touring bike, I would assume touring in all conditions. Will you build this motor to run on any gas and run cool enough to retain longevity? This could mean a lower comp build, a real oil cooler setup or even fans. Will you need to install an aftermarket clutch? likely and do you mind the extra lever pull that is most times necessary?  Will the rest of your drive train hold up to long term touring? I have two bikes in right now with failed output bearings on the cruise drive trans.
Will you need a chain setup if you are an aggressive rider?  A good 113 build will make most people very happy for both cruising and longevity, unhappy when your buddy with the 124 passes you.
A 124 will make you very happy when you roll that throttle, not so happy sitting in line at Sturgis looking for a parking spot
As far as best bang for the buck the price of these engine sizes will vary little.
Whatever you decide, build this motor to run cool and don't push it to the bleeding edge for what after all is a street bike.

Thanks BVHOG! Those are some good points but I am somewhat aware of what Im getting into. Im currently riding my second built touring bike and for me there's nothing like having a big bike with big power and Ill ride in any kind of weather. The 113 I have does really well however it doesn't like sitting in traffic real well in hot weather though, I need to try a different tuner to see if its tune related or just the nature of the beast but that's another issue, there aren't a lot of good tuners in Georgia that I know of. When I built it reliability was top priority so it got a Baker 7 speed and Attitude adjuster, Primo pro clutch w/vpp, the heavy duty throw out and output bearings and a Baker comp. I like to do it once and right and don't mind spending the money to get it there because I'd rather enjoy my money than spend it on tow trucks and shop bills. That is what I appreciate about this forum, the guys with the know how and experience try to steer those like myself in the right direction. I may end up not building another but if I get the opportunity I think Id like to build a RG and see if I can top what I have and hopefully be able to use some of the vendors here to make it happen. I learn something every time I login and again I really appreciate everyone's input! 

[Azgunner]

I've had an 88", 95", 117", & now an S&S 124 LC crate motor in my '02 Dyna. The 117" was a great motor & a lot of fun jumping up from the 95". The 124" is a lot more fun though! Even when I had stock headers & Cycle Shack slip-ons making 120hp/130tq on a ballpark tune the bike felt like a beast. Now I've got a better tune & Bassani Pro-Streets exh. making 132hp/141tq & this thing is one nasty sounding monster that goes faster than I need it to. Stock S&S motor w/ one year warranty that S&S absolutely stands behind, mild compression for touring, & an abundance of S&S dealers, at least in my area, if you do have a problem seems like a pretty good deal IMHO.

This 124" has more power & runs 20°-30° cooler than my 117", though I did also change from a 6-row to a 10-row Jagg oil cooler. The head temps are also 30°+ cooler as well.

I'm not a H-D mechanical/performance guru at all though I'm slowly learning a few things here & there thanks to those on this forum who are. I do love to ride & go fast when I want to. Knowing what I know now I would absolutely buy a 124" crate motor again.

[rhuff]

I came from a factory 95" stage 2 on my 03 King.  Was okay.  Had a 107" all bore built by Randy at Hyperformance and tuned by BVBOB last spring.  LOVE IT.  But what I wished I would have done is go 117" or 124" after 15,000 miles and close to 2 years of riding it.  I've never dumped the clutch, pulled a wheelie, etc., but I love to ride the "Potty mouth" out of it in the twisties (albeit that 03 frame is a whole 'nother story and really shouldn't have anymore than the 115/115 I have in it). 

So when the time comes to punch out my 15 RGS, I'll likely just go to 124" either from my cases or S&S LC.  I don't need it to be ridiculous.  Just really ride-able and meant for touring.  125 horse and 135 TQ would make me happy.